The present invention generally pertains to processing data signals produced from an array of charge injection device (CID) radiation detector elements, and is particularly directed toward increasing the effective dynamic range of the detector array.
CID radiation detector arrays are useful for producing data signals that may be processed to provide images of objects that emit radiation in a distinct frequency band, such as infrared radiation. A staring mosaic planar array of indium antimonide (InSb) CID infrared radiation detector elements is preferred for an infrared radiation imaging system requiring a large total field of view without requiring an opto-mechanical scanning system.
However, the inherent dynamic range of state-of-the-art CID infrared detector elements, such as InSb is insufficient for many applications such as in a missile tracking system, or in a ground target detection system. Low sensitivity problems arise when trying to differentiate between low temperature contract objects in a scene when the detector array has a limited dynamic range.
Mosaic arrays of CID infrared detector elements also inherently have a fixed pattern noise problem, which arises from the finite differences in responsivities (both A.C. and D.C.) of the detector elements. Non-uniformities ranging from .+-.5 percent to .+-.20 percent effectively mask small temperature variations such as are encountered with tactical targets in high-clutter backgrounds.